>Why would Google not simply shut Chrome down?

Because they'd get less tracking info and have a harder time tracking people across the web? That seems the biggest point here.

Google keeps Chrome around because the alternative is just too risky for their core business. If (for example) everyone used IE then Microsoft would be able to shut out Google's ads.

It's not just ads. It's also Microsoft's ecosystem around Windows and Office. From Outlook, Sharepoint, to XBox, to 3rd party automation tools like BluePrism, UIPath, AutomationAnywhere that are tools built around IE and are getting a lot of traction in corporations at the moment. And probably a lot more tools I don't know about.

That's what I thought too (ie. that Google is critically dependent on web browsers that don't discriminate against Google somehow, and is paying for two such browsers). But so many people say that Chrome and Firefox are competitors that I'm curious to hear arguments for that.

Owning a browser is a business as every search engine wants to be the default. I think google is forking several billions a year to be the default on Safari and is probably Firefox’ primary source of revenues.

I don’t know if Microsoft has any other motivation for Edge other than being the front end for Bing.

Chrome is a strategic tool for Google that they use to funnel users to their services, collect data and influence web standards in their favor (among other things).

You are asking why controlling the default search engine and the client infrastructure for tracking users is valuable to Google?

No, not at all.

I am asking why people (appear to) think that Google's own browser is competing against the other browser that Google also funds.

Otherwise it would lose market share and money.

Why?

I may be stupid here. Please excuse if so. But I don't see why Google would lose market share in a market that provides income if Firefox' market share were higher and Chrome's lower.